Enzymes- Properties, Classification and Significance


Enzymes are biological catalysts that increase the rate of chemical reactions without being changed themselves in the process. They are essential for life because they allow biochemical reactions to occur under mild conditions (such as low temperature, atmospheric pressure and neutral pH) that are compatible with living cells.

Enzymes are mostly proteins, although some RNA molecules can also act as enzymes. Enzymes have specific three-dimensional shapes that determine their functions and interactions with other molecules. The region of an enzyme that binds and transforms the substrate (the molecule that undergoes the reaction) is called the active site. The active site is usually a small part of the enzyme that is formed by amino acid residues that may be far apart in the linear sequence of the protein.

Enzymes are highly specific for their substrates and products, meaning that they only catalyze one type of reaction or a few closely related reactions. This specificity is determined by the shape and properties of the active site, which can only accommodate certain substrates and facilitate certain transformations. For example, sucrase is an enzyme that catalyzes the hydrolysis of sucrose into glucose and fructose, but it cannot hydrolyze other disaccharides such as lactose or maltose.

Enzyme activity can be regulated by various factors, such as temperature, pH, substrate concentration, inhibitors, activators and feedback mechanisms. Enzymes usually have an optimal temperature and pH at which they function most efficiently. For example, pepsin is an enzyme that digests proteins in the stomach and has an optimal pH of 2, while trypsin is an enzyme that digests proteins in the small intestine and has an optimal pH of 8.5. Enzyme activity can also be modulated by molecules that bind to the enzyme and either enhance or reduce its catalytic ability. These molecules can be either reversible or irreversible inhibitors or activators. Furthermore, some enzymes are regulated by feedback mechanisms, where the product of a reaction inhibits or activates the enzyme that catalyzes it or another enzyme in the same pathway.

Enzymes are classified into six major classes based on the type of reaction they catalyze: oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases. Each enzyme has a unique name and a four-digit classification number assigned by the Enzyme Commission (EC). For example, trypsin has the EC number, which indicates that it belongs to the class of hydrolases (3), sub-class of proteases (4), sub-sub-class of serine proteases (21) and serial number (4).

Enzymes have many roles and applications in biological systems and beyond. They are involved in metabolism, gene expression, signal transduction, cell division, defense mechanisms and many other processes. They also have industrial and medical uses, such as in food production, biotechnology, diagnostics, drug delivery and therapy.